1. Field of the Invention
The present invention relates to an ultrasonic sensor device and an ultrasonic transducer.
2. Description of Related Art
Conventionally, Japanese Unexamined Patent Publication No. 2003-32794 corresponding to EP No. 0881624B1 discloses that an ultrasonic sensor, which includes an ultrasonic transducer received in a hollow case. Here, the ultrasonic transducer includes a housing with a bottom, a piezoelectric element, which is fixed to an inner surface of the bottom. The bottom of the housing serves as a vibrating surface.
Generally, the thus ultrasonic sensor is assembled to, for example, a bumper of a vehicle so that the ultrasonic sensor serves as an obstacle sensor to detect obstacles around the vehicle.
In this case, the ultrasonic sensor is typically located at a position such that the vibrating surface of the ultrasonic transducer is exposed outside of the vehicle. Therefore, an object (e.g., a flying stone) may directly collide with the vibrating surface, thereby damaging the ultrasonic transducer.